Figure13a
Figure13b
If we wish to integratewith respectto the -axis,we haveto solvefor in termsof That wouldnot be
easy(try it!). An easierway is to integratewith respectto the -axisby usingthe shellmethod.Hereis
how:A cylindricalshell is a solid enclosedby two concentriccylinders.If the innerradiusis and the outer
one is with both of height then the volumeis (Figure14)